Wash the Brussels sprouts, remove loose leaves and cook the florets in relatively little (the vegetables should be covered - if necessary, add a little more water if they are completely absorbed before the end of the cooking time) lightly salted water - the cooker, the creamier it will be the final result.
When the water is almost absorbed, add the butter and the grated Parmesan, stir well and let it steep for a few minutes on a low flame. The whole thing should have a nice creamy consistency (the outer leaves loosen and mix with the butter and melted cheese). Finally grind fresh pepper over it.
The amount is enough for 4 side dishes or 2 main dishes.